in response, the u.s. navy said none of its unmanned aerial vehicles-- u.a.v.'s-- are missing. and in washington, white house spokesman jay carney raised doubts about tehran's statements. we have no evidence that the iranian claims you cite are true. i'd refer you to the pentagon's comments this morning for details about this particular type of u.a.v., but again we have no evidence that the iranian claims are true. >> sreenivasan: a year ago, iran did manage to down a c.i.a. drone that apparently crossed the border from afghanistan. and last month, the u.s. military said another drone came under fire by iran over the persian gulf. it was undamaged. in afghanistan, a bomb blast has killed two nato troops in the country's south. the alliance says the attack happened yesterday. it did not provide the nationalities of those killed. so far this year at least 384 international troops have been killed in afghanistan. most of them have been americans. in economic news, the u.s. housing market showed more signs of recovery in a new report by the real estate data firm, core logic. it sai